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How To Deal With Hydroids On Your Aquarium Glass!

There are a wide range of pests that can work their way into your tank within the fish keeping hobby but one of the most troublesome to actually get rid of are hydroids.

Not only are they very resilient to chemical treatments to remove them but very few fish will reliably remove them and physically removing them one at a time is very difficult so we often see people reaching out and asking about removing hydroids on glass in their aquarium.

If you have lots of hydroids on your aquarium glass then you can usually remove them with a cheap car windshield cleaning tool allowing you to remove large number of hydroids from your glass at once.

If you only have a small number of hydroids on your glass then the task becomes more difficult and you may have to try manually removing them one at a time.

As we covered in our article on common hydroid questions that we see people asking, the breeding speed of hydroids is surprisingly fast so even if you are able to remove large numbers of hydroids from your aquarium glass, they can quickly come back.

Even a small number of hydroids hiding somewhere else in the tank and rapidly reproduce so some people do choose to empty their aquarium and deep clean it if they are having problems with hydroids.

What Are These Hydroids On My Aquarium Glass?

Hydroids are tiny predators that are related to jellyfish with some species of hydroids being known to sting fish and other things in their tank causing a number of problems.

Some people also find hydroids visually unappealing in their aquarium due to clouding the water or making the aquarium glass in large numbers so most people look to remove them as quickly as possible.

It is usually easier to see hydroids on your aquarium glass due to it being the main way to view an aquarium but they will also live on substrate, rocks, plants, and even fish in some cases.

This is why it is so difficult to reliably remove them from your tank as most people only focus on the hydroids on their glass as they are the easiest ones to see only for the hydroids in their tank in other locations to just breed and replace the ones you removed.

Many people think that hydroids are copepods, amphipods, rotifers or phytoplankton but they are a totally different type of animal. It can be difficult to remove copepods from your aquarium glass but hydroids are usually far more difficult to deal with.

This is why we would highly recommend that you take steps to get the hydroids out of your aquarium as quickly as possible and as soon as you notice them before their numbers start to rapidly swell.

How Do You Get Hydroids Off Aquarium Glass?

The most reliable way to get hydroids off your aquarium glass is to physically remove them with some type of tool with a cheap car windshield cleaning tool often being one of the better options.

Some people swear by using an old toothbrush to detach smaller numbers of hydroids from your aquarium glass but this can just let them flow in your water to a different area of your aquarium.

We have seen some people say that they have had great success with removing hydroids from their aquarium by using various types of parasitic treatments for the fish keeping hobby.

Hydroids are surprisingly resilient to chemicals so it is more likely that the reports you see on social media of people saying they use something like Melafix to remove hydroids from their tank actually had copepods or something that looks similar to hydroids.

Depending on your aquarium setup, you may be able to tweak the nutrient levels in your water to starve the hydroids but this will not be a viable option for everyone.

We would not recommend that you try this method if you are new to fish keeping too as you have to make sure that the nutrient load for the tank is balanced so everything that needs nutrients in the tank has it with minimal surplus nutrients being left over for the hydroids.

What Will Eat Hydroids Living On Aquarium Glass?

Very few fish will actually eat hydroids in your aquarium but some butterfly fish and a most types of angelfish will usually eat some of the hydroids on your aquarium glass due to them being easy for the fish to find.

There are some other species of fish that may eat hydroids but it is not a reliable way to remove the hydroids from your aquarium.

Some people say that they have been able to add new fish to their aquarium to deal with the hydroids on their glass but we always feel that this could also just be people misidentifying hydroids as copepods or something else.

Even if you do manage to find a fish that will reliably eat large amounts of hydroids you still have new fish in your aquarium once the hydroids that may not be suitable to keep with the other fish in the tank too.

It is also very rare that snails or shrimp will eat hydroids in an aquarium too.

Even though you can see a small number of people on social media saying that the snails in their tank were eating the hydroids on their glass, rocks, and substrate, we find this doubtful and feel that the tank was probably having issues with copepods rather than hydroids.

Do Hydroids Damage Aquarium Glass?

Overextended periods of time, dead hydroids can end up calcifying onto your aquarium glass with these marks being difficult to remove unless you empty your tank and use chemicals to dissolve the calcium.

If this happens to enough hydroids in your tank then they really an add a frosted look to parts of your aquarium glass and ruin the viewing pleasure of your tank.

It is unlikely that hydroids will be able to actually damage your aquarium glass to a level where the structural integrity of your glass is at risk and water may be able to escape from the tank.

The majority of the “damage” that people report from hydroids is just calcified remains of hydroids on the glass and is not actual damage to the glass due to hydroids trying to eat it as some people claim.


That brings our article going over what to do about hydroids on aquarium glass to an end. We hope that we have been able to help you better understand what you should be doing to deal with a breakout of hydroids in your aquarium but they really are a pain to deal with. There is a constant stream of people reaching out and asking how they can get rid of hydroids in their aquarium but it is not easy and takes time and effort and even then, it can be difficult to remove them all from your tank.